1. Field of the Invention
The present invention relates to a sensor attachment structure in an image capturing apparatus such as a digital camera and an electronic spirit level control technology.
2. Description of the Related Art
Recently image capturing apparatus have been proposed such as a digital camera having a function of notifying a user of the degree and direction of its inclination from the horizontal plane or a function of detecting the inclination amount of a captured image and correcting the image inclination by post-processing so as to capture an inclination-free image. These image capturing apparatus include an acceleration sensor to detect inclination.
For example, in Japanese Patent Laid-Open No. 2004-343476, an inclination sensor (acceleration sensor) having two measurement axes is arranged by directing one measurement axis in the horizontal direction and the other in the vertical direction, thereby detecting the inclination degree of the camera in each of its landscape orientation and portrait orientation. The technique disclosed in Japanese Patent Laid-Open No. 2004-343476 changes the measurement axis in accordance with the orientation of the camera under the concept that measurement is done by selectively using a more sensitive measurement axis of the acceleration sensor. For example, in the landscape orientation, the inclination degree from the horizontal plane is measured using the first measurement axis which is arranged in the horizontal direction in that state so as to ensure a high sensitivity of the sensor. When the camera is placed in the portrait orientation, the inclination degree from the horizontal plane is measured using the second measurement axis that is arranged in the horizontal direction in that state so as to ensure a high sensitivity of the sensor. This implements more accurate inclination degree detection.
In the technique described in Japanese Patent Laid-Open No. 2004-343476, however, when arranging the acceleration sensor on a board, the component mounted positions and the attachment position of the board with the mounted components need to be strictly aligned in the roll direction around the imaging optical axis. The reason is as follows. Unless the measurement axis is arranged in the horizontal direction almost without misalignment, when the user swings the camera in the pitch direction, the horizontal point of the measurement axis is shifted by the influence of gravity in the pitch direction even after offset adjustment of the horizontal point. Additionally, if the characteristic such as the sensitivity of the acceleration sensor changes due to the temperature, the horizontal point shifts as the ambient temperature changes. Furthermore, since the measurement axis changes in accordance with the orientation of the camera, the camera needs to be set in two orientations for offset adjustment of the two measurement axes when adjusting offset of the horizontal point at the time of shipment from a factory, resulting in a more complex adjustment process.